Safe.



PATENTED APR. 14, 1903.

J. WARTENBERGER.

SAPR

APPLIUATION FILED 00'1'. 3o, 1900.

N'o MoDEL.

UNITED STATES l PATENT OEEICE.

JOSEF WARTENBERGER, OF BERLIN, GERMANY.

SAFE.v

SPECIFICATION forming part of Lettere Patent N o. 725,303, dated April 14, 1903. Application filed October 301900. Serial No. 34,896. (No model.)

To @ZZ whom tm/ay concern:

Be it known that I, JosEE WARTENBERGER, a subject of the Emperor of Germany, residing at Berlin, Germany, have invented a new and useful Improvement in Safes or the Like, of which the following is a full, clear,r and exact description;

The mixture of aluminium and ferric oxid known in commerce as thermit is capable of developing sufficient heat to smelt every kind of material hitherto known. Therefore considerable danger exists that this new medium might easily be employed for destroying or melting through the armor-plates of safes and strong rooms, since theingredients necessary for forming andigniting the thermit may be easily obtained in commerce. It is therefore necessary that safe and strong-room manufacturers should find some means of re-l sisting attacks made by the aid of thermit. Experiments have shown that iron, steel, and cement are quite incapable of such resistance.

The object of the present invention is to provide effective protection against the melting power of thermit, particularly in regard to safes and strong rooms.

The principle upon which the present invention is based' is the prevention of a continued contact of the thermit with the plate onto which it is poured. This object is attained by employing metals or metallic alloys for the construction of the safe or strong room which under the influence of the heat of the thermit poured on the same generate vapors capable of explosion, whereby part of the thermit will be-blown off, while at the same time the contact of the material not yet' attacked with the thermit will be prevented,

in that a layer of`vapor will be formed be tween the two, which will prevent the imme` diate transmission of the heat of the thermit.V

It has been discoveredthat this effect` may beL best attained with the aid of metals having a comparatively low melting-point-such as zinc, lead, tin, copper, antimony, bismuth, and alloys of the same. The heat of the thermit momentarily decomposes the metal or alloy, so that at first, if zinc or zinc alloys are employed, zinc-vapors will be developed on the surface, which, owing to the intense rapidity of the development, will blow off the greater part of the mass poured on by the explosive eruption.v "The reaction is analogous to the Leidenfrostphenomenon,whichiswellknown. The slag of the thermit remaining on the surface combines with the metal of the plate to form an insoluble crust, which renders the attack by a renewed addition of thermit less effective.

The-particular proportions of the protecting metal to be employed may be varied within considerable limits, and many other substances maybe added to the metallic alloy which may advantageously aect the protecting metal in View of the object to be attained.

It is,however,a condition that the alloy should contain a considerable proportion of the above-men tioned substances. There is a further advantage in the employment of zinc, to wit: When the thermit is poured onto the armor-plate, such a `quantity of zinc-vapors will be generated (which are, as is well known,

' very poisonous) that it will be practicallyimpossible for-an y person to remain in a closed room and continue to work on the destruction of the safe and extraction of its contents.

yThis effect may be increased by adding phosphorus and similar substances t0 thev protecting mass.

The application of the invention is illustrated in the accompanying drawing, which is asectional detail of a corner of a safe.

A is the door of -the safe, and B is a side wall ofthe same. 1

a is 'Wrought-iron.

b is steel, and c is the plate of a more fusible and volatile metal protecting the safe from the effects of the thermit. Y

The. further construction of the safe is usual.

d is a layer of infusorialearth, and e is a lock-bolt.

As shown in the drawing, the protectioni plate c is covered on both sides by steel or armor plates. The plates on the outer side of the plate c are necessary, as otherwise the soft'metal can easily be cut or boredaway, and so the purpose of the plate c will be null and Void; but if these plates are arranged as roo shown it is impossible to bore the safe; but it is possible to smelt the same with thermit.

As soon as the first two iron or steel plates are smelted the thermit acts on plate c, of a more fusible and volatile metal, with the result stated in the specification. It will be therefore impossible to Smelt also the steel plates lying behind the plate c.

I claim as my invention- In a safe or the like, the combination with the steel or iron plates forming the walls xo thereof, of plates of soft metal other than iron 

